Immunodeficiency Disorders Overview
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Questions and Answers

What is the primary consequence of platelet dysfunction?

  • Inflammatory response disorders
  • Bleeding disorders (correct)
  • Increased likelihood of autoimmune diseases
  • Enhanced bacterial infections

    • What characterizes Chédiak-Higashi syndrome?

  • Impaired complement function
  • Excessive platelet aggregation
  • Defective neutrophil chemotaxis (correct)
  • B-cell maturation abnormalities

    • Which complement deficiencies are associated with increased infections from encapsulated organisms?

  • Deficiency of C1, 4, or 2 (correct)
  • Deficiency of C5
  • Deficiency of C3
  • Deficiency of C7

    • How are most complement deficiencies inherited?

    <p>Autosomal dominant traits (A)</p> Signup and view all the answers

    What role does the membrane attack complex (MAC) play in the immune response?

    <p>Destroys Gram-negative bacteria (B)</p> Signup and view all the answers

    Which condition is characterized by impaired development and/or function of T lymphocytes?

    <p>Combined immunodeficiencies (B)</p> Signup and view all the answers

    What is often the cause of defective antibody responses in conditions like X-linked agammaglobulinemia?

    <p>Intrinsic B cell abnormalities (C)</p> Signup and view all the answers

    Patients with defects in B cell function are likely to experience which of the following?

    <p>Recurrent pyogenic infections (A)</p> Signup and view all the answers

    What role do IgG and IgM play in the absence of IgA?

    <p>They compensate for the lack of IgA, often making the deficiency go unnoticed. (D)</p> Signup and view all the answers

    What is a consequence of defects in T cell function?

    <p>Susceptibility to opportunistic infections. (B)</p> Signup and view all the answers

    What condition is characterized by the absence of the thymus?

    <p>Di George Syndrome (B)</p> Signup and view all the answers

    Which of the following best describes SCID?

    <p>It presents with severe bacterial, viral, and fungal infections within the first six months of life. (B)</p> Signup and view all the answers

    What is one major cause of secondary immunodeficiency?

    <p>Malnutrition. (C)</p> Signup and view all the answers

    Which factor can lead to immunodeficiency due to prolonged serious disorder?

    <p>Chronic disease such as diabetes. (D)</p> Signup and view all the answers

    What is a defining feature of T cell immunodeficiencies?

    <p>Defective T-dependent B cell responses. (D)</p> Signup and view all the answers

    What is the most profound effect of SCID on the immune response?

    <p>Lack of T cells. (B)</p> Signup and view all the answers

    What is the primary consequence of severe protein-energy malnutrition (PEM) on the immune system?

    <p>Reduced efficacy of the immune system (B)</p> Signup and view all the answers

    Which trace elements are crucial for maintaining a strong immune response?

    <p>Iron, selenium, copper, and zinc (B)</p> Signup and view all the answers

    How does the human immunodeficiency virus (HIV) primarily affect the immune system?

    <p>By targeting CD4 T cells and macrophages (B)</p> Signup and view all the answers

    What role do vitamins A, B6, C, E and folic acid play in the immune system?

    <p>They enhance overall resistance to infection (C)</p> Signup and view all the answers

    What is a common effect of immunomodulatory drugs on immune function?

    <p>They severely depress immune functions (C)</p> Signup and view all the answers

    Which of the following correctly describes the transmission routes of HIV?

    <p>Sexual contact, contaminated needles/blood products, and vertical transmission (C)</p> Signup and view all the answers

    What is a significant risk that develops if HIV remains untreated?

    <p>Acquired immunodeficiency syndrome (AIDS) (D)</p> Signup and view all the answers

    What is the primary consequence of X-linked (Bruton) Agammaglobulinemia?

    <p>Inability to produce B cells and plasma cells (C)</p> Signup and view all the answers

    What effect do carotenoids have on immune function?

    <p>They enhance NK cell activity and stimulate cytokine production (C)</p> Signup and view all the answers

    What critical protein is lacking in X-linked (Bruton) Agammaglobulinemia, preventing B cell maturation?

    <p>Cytoplasmic tyrosine kinase (B)</p> Signup and view all the answers

    Which clinical presentation is most commonly associated with X-linked hyper-IgM syndrome?

    <p>Defective heavy-chain isotype switching (C)</p> Signup and view all the answers

    What key function is impaired in patients with X-linked hyper-IgM syndrome due to defects in CD40 ligand?

    <p>B cell activation and isotype switching (A)</p> Signup and view all the answers

    Which of the following describes the immune response in patients with selective IgA deficiency?

    <p>Chronic infections at mucosal surfaces (A)</p> Signup and view all the answers

    Why do symptoms of X-linked (Bruton) Agammaglobulinemia typically manifest after the first year of life?

    <p>Initial antibody production from maternal IgG (C)</p> Signup and view all the answers

    Which factor is crucial for the interaction between activated T cells and macrophages in X-linked hyper-IgM syndrome?

    <p>CD40 ligand (D)</p> Signup and view all the answers

    What kind of infections are prevalent in patients with X-linked hyper-IgM syndrome due to impaired cell-mediated immunity?

    <p>Intracellular microbial infections (D)</p> Signup and view all the answers

    What is the underlying cause of chronic granulomatous disease?

    <p>Mutations in genes encoding NADPH oxidase (A)</p> Signup and view all the answers

    Which type of infections are patients with chronic granulomatous disease particularly prone to?

    <p>Opportunistic infections with certain bacteria and fungi (A)</p> Signup and view all the answers

    What is a characteristic feature of Chediak-Higashi syndrome?

    <p>Presence of large granular inclusions in white blood cells (A)</p> Signup and view all the answers

    In chronic granulomatous disease, which mechanism is impaired leading to difficulty in killing microbes?

    <p>Production of microbicidal reactive oxygen species (D)</p> Signup and view all the answers

    What mechanism do catalase-positive bacteria use to evade killing by leukocytes in chronic granulomatous disease?

    <p>Degradation of hydrogen peroxide (D)</p> Signup and view all the answers

    Which syndrome is characterized by impaired intracellular killing and lymphoreticular cancer due to defective lysosomal function?

    <p>Chediak-Higashi syndrome (D)</p> Signup and view all the answers

    What is one of the main clinical presentations of myeloperoxidase deficiency?

    <p>Recurrent candidial infections (B)</p> Signup and view all the answers

    What is a key characteristic of Lazy Leucocyte syndrome?

    <p>Poor functional response of leukocytes (C)</p> Signup and view all the answers

    What characterizes primary immunodeficiency diseases (PIDs)?

    <p>They result from intrinsic defects in the immune system. (D)</p> Signup and view all the answers

    Which of the following is a feature of congenital agranulocytosis (Kostmann syndrome)?

    <p>Defect in the gene inducing G-CSF. (D)</p> Signup and view all the answers

    Which of the following best describes secondary (acquired) immune deficiency?

    <p>It results from infections such as HIV. (D)</p> Signup and view all the answers

    What is a common consequence of defects in innate immunity?

    <p>Impaired function of phagocytes. (A)</p> Signup and view all the answers

    What type of deficiencies are caused by genetically-determined defects in the complement system?

    <p>Complement deficiencies. (B)</p> Signup and view all the answers

    Which of the following illnesses is NOT typically associated with congenital agranulocytosis?

    <p>Non-Hodgkin lymphoma. (D)</p> Signup and view all the answers

    What treatment is commonly used for patients with congenital agranulocytosis?

    <p>Granulocyte-macrophage colony stimulating factor. (C)</p> Signup and view all the answers

    Phagocytic dysfunctions are primarily related to deficiencies in what area?

    <p>Enzymatic pathways in phagocytes. (C)</p> Signup and view all the answers

    Flashcards

    Primary Immunodeficiency

    A condition where the immune system is weakened, often due to a genetic defect.

    Secondary Immunodeficiency

    A condition where the immune system is weakened due to external factors like infection or treatments.

    IgA Deficiency

    A type of primary immunodeficiency where there is a lack of IgA antibodies.

    T Cell Immunodeficiency

    A type of primary immunodeficiency where there is a deficiency in T cell function.

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    Congenital Thymic Hypoplasia (DiGeorge Syndrome)

    A type of T cell immunodeficiency caused by the absence of the thymus gland.

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    Severe Combined Immune Deficiency (SCID)

    A severe type of primary immunodeficiency where both B and T cell function are defective.

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    Malnutrition and Immunodeficiency

    Malnutrition can compromise the immune system, making it vulnerable to infections.

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    Viral Infections and Immunodeficiency

    Viral infections, such as HIV, can suppress the immune system, leading to immunodeficiency.

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    Secondary (Acquired) Immunodeficiency

    A group of disorders where the immune system is compromised due to external factors like infections, medications, or nutritional deficiencies.

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    Defects in Innate Immunity

    Immune deficiencies that arise from problems with the innate immune system, which is the body's first line of defense against infections.

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    Congenital Agranulocytosis (Kostmann Syndrome)

    A rare genetic condition where there is a deficiency in neutrophils, a type of white blood cell that fights bacteria.

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    Phagocytic Dysfunction

    Disorders that affect the ability of phagocytes, cells that engulf and destroy pathogens, to function properly.

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    Defect in the gene inducing G-CSF

    A genetic condition where certain genes responsible for the development of neutrophils are faulty.

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    Complement Deficiencies

    A group of disorders that affect components of the complement system, a part of the immune system that helps with the destruction of pathogens.

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    Quantitative Disorder

    Disorders that are characterized by a reduced number of immune cells, particularly neutrophils.

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    Chronic Granulomatous Disease (CGD)

    An X-linked disorder affecting phagocyte NADPH oxidase, causing recurrent infections with catalase-positive bacteria due to impaired intracellular killing of bacteria and fungi.

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    NADPH Oxidase

    An enzyme critical for producing reactive oxygen species (ROS) within phagocytes, essential for killing microbes.

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    Granuloma

    A collection of macrophages that accumulate around sites of persistent infection, often seen in CGD due to the failure of neutrophils to effectively kill pathogens.

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    Myeloperoxidase Deficiency

    An inherited disorder affecting the ability of leukocytes (especially neutrophils) to kill phagocytosed microbes, characterized by recurrent infections.

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    Chediak-Higashi Syndrome

    An autosomal recessive disorder characterized by defective fusion of phagosomes and lysosomes, leading to recurrent infections and other symptoms.

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    Lazy Leukocyte Syndrome

    A rare genetic disorder characterized by defective migration of neutrophils, leading to delayed recruitment to sites of infection.

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    Glucose-6-Phosphate Dehydrogenase (G6PD)

    An enzyme required for the breakdown of glucose, its deficiency can lead to a syndrome similar to CGD, particularly affecting red blood cells.

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    Immunodeficiency

    A state where the immune system is weakened, making the body more susceptible to infections.

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    Malnutrition

    A condition where the body lacks sufficient nutrients, leading to a weakened immune system and increased risk of infections.

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    PEM (Protein-Energy Malnutrition)

    A severe form of malnutrition characterized by protein and energy deficiencies.

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    Trace Elements (Iron, Selenium, Copper, Zinc)

    Essential minerals that play a crucial role in immune function.

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    Vitamins A, B6, C, E, and Folic Acid

    Vitamins vital for overall immune resistance and fighting off infections.

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    Immunomodulatory Drugs

    Medications that can suppress the immune system.

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    HIV (Human Immunodeficiency Virus)

    A virus that primarily targets CD4+ T cells, leading to a weakened immune system.

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    AIDS (Acquired Immunodeficiency Syndrome)

    The final stage of HIV infection, characterized by a severely compromised immune system.

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    X-linked (Bruton) Agammaglobulinemia

    A genetic disorder that affects B-cell development, leading to a complete absence of B cells, plasma cells, and immunoglobulins.

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    X-linked Hyper-IgM Syndrome

    A disorder that prevents B cells from switching from IgM to other antibody classes like IgG and IgA.

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    Selective IgA Deficiency

    A rare condition where the body does not produce enough IgA, the antibody responsible for protecting mucous membranes.

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    CD40 Ligand (CD40L)

    The protein that binds to CD40 on B cells, dendritic cells, and macrophages, essential for T cell-dependent activation.

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    Class Switching

    The process by which B cells switch from producing IgM to producing other antibody classes (IgG, IgA, IgE).

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    Cytoplasmic Tyrosine Kinase

    A cytoplasmic tyrosine kinase crucial for B cell maturation and immunoglobulin production.

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    CD40

    A protein that binds to CD40L on T cells, important for B cell activation and class switching.

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    IgM

    The primary antibody produced by B cells, responsible for the initial response to an antigen.

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    Complement Deficiency States

    Various deficiencies in complement proteins, affecting immune responses like opsonisation, bacterial killing, and chemotaxis.

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    Defects in B cell function

    Defects in B lymphocytes which lead to reduced antibody production, increasing susceptibility to bacterial infections.

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    Combined immunodeficiencies

    Disorders affecting both T and B lymphocyte development and function, significantly impairing immune responses.

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    Defects in Lymphocyte Maturation

    Defects in the maturation and development of B lymphocytes, resulting in compromised antibody production.

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    Deficiencies of the late complement components (C5-C9)

    A condition where late components of the complement system (C5-C9) are deficient, interfering with the formation of the Membrane Attack Complex (MAC).

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    Deficiencies of the early complement components (C1, C4, C2, and C3)

    Defects in the early components of the complement system (C1, C4, C2, and C3), leading to impaired opsonization and increased susceptibility to encapsulated bacteria

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    Study Notes

    Immunodeficiency States

    • Immunodeficiency disorders are a diverse group of illnesses arising from abnormalities in the immune system, making individuals susceptible to infections.
    • Immune system abnormalities can involve the absence or malfunction of blood cells (lymphocytes, granulocytes, monocytes) or soluble molecules (antibodies, complement components).
    • Immune deficiency states are categorized into primary and secondary types.

    Primary Immunodeficiency

    • Primary immunodeficiencies (PIDs) are disorders resulting from hereditary or intrinsic defects in the immune system.
    • PIDs encompass a diverse group of disorders characterized by defects in the development or function of the immune system.
    • These defects originate from intrinsic cellular and mediator deficiencies in either innate or adaptive immunity.
    • The classification of PIDs is based on the underlying immunological defect.

    Innate Immunity Defects

    • Defects in phagocytes and the complement system often result in immunodeficiency.
    • Phagocytic cell disorders involve inadequacies in the development and/or function of myeloid cells (granulocytes and macrophages).
    • Genetically-determined defects of the complement system's functional or regulatory components lead to complement deficiencies.
    • Leukocyte defects include both quantitative and qualitative abnormalities.

    Quantitative Leukocyte Defects

    • Congenital agranulocytosis (Kostmann syndrome) is characterized by a gene defect that hinders G-CSF (granulocyte colony stimulating factor) production, leading to a decline in neutrophil counts and impaired myeloid progenitor cell differentiation.
    • Affected patients exhibit features such as pneumonia, otitis media, gingivostomatitis, and perineal abscesses.

    Phagocytic Dysfunction

    • Primary or intrinsic issues in phagocytes are linked to enzymatic deficiencies within the metabolic pathways essential for microbial killing.
    • Chronic granulomatous disease results from NADPH oxidase deficiencies, causing impaired microbial killing within macrophages and neutrophils.
    • Myeloperoxidase deficiency, Chediak-Higashi syndrome, and Lazy Leukocyte syndrome also fall under the category of phagocytic dysfunction.

    Chronic Granulomatous Disease

    • Chronic granulomatous disease (CGD) is an X-linked disorder typically manifesting in the first two years of life.
    • CGD arises from mutations affecting gene encoding subunits of NADPH oxidase, which catalyzes the production of reactive oxygen species vital for microbial destruction.
    • Patients with CGD exhibit susceptibility to infections stemming from impaired intracellular killing of bacteria and fungi. They commonly experience recurrent infections with catalase-positive bacteria, such as staphylococci.

    Specific Enzyme Deficiencies

    • Complete deficiency of glucose-6-phosphate dehydrogenase (G6PD) in leukocytes results in a syndrome mimicking chronic granulomatous disease, exhibiting a later onset.
    • This condition affects both genders and frequently co-occurs with hemolytic anemia. Meanwhile, myeloperoxidase deficiency results in impaired intracellular killing, leading to candidial and staphylococcal infections.

    Chediak-Higashi Syndrome

    • Chediak-Higashi syndrome is an autosomal recessive multi-system disorder characterized by recurrent bacterial infections, hepatosplenomegaly, central nervous system abnormalities, and a high incidence of lymphoreticular cancers.
    • The primary defect is abnormal intracellular killing due to defective phagosome-lysosome fusion, indicated by abnormal giant granules in white blood cells.
    • Patients with this disorder often exhibit albinism, as melanocyte dysfunction prevents pigment transfer to keratinocytes and other epithelial cells.
    • The syndrome is also associated with platelet abnormalities that can contribute to bleeding disorders due to platelet dysfunction.

    Lazy Leukocyte Syndrome

    • Lazy Leukocyte Syndrome affects neutrophil chemotaxis and is linked with neutropenia.
    • This condition predisposes individuals to severe bacterial infections.

    Complement Deficiency States

    • Various complement deficiencies and functional abnormalities lead to increased susceptibility to infections.
    • Complement proteins are essential for opsonization, bacterial killing, and chemotaxis.
    • Deficiency in early complement components (e.g., C1, C4, C2, or C3) can increase susceptibility to encapsulated organisms (such as Streptococcus pneumoniae, Streptococcus pyogenes, and Haemophilus influenzae).
    • Deficiencies in late complement components (e.g., C5-C9) impair the formation of the membrane attack complex (MAC).

    Defects in Lymphocyte Maturation

    • Antibody deficiencies reflect impaired B cell function due to abnormalities in intrinsic B cells or defects in T cells that affect B cell activation and maturation.
    • Combined immunodeficiencies are characterized by impaired development and/or function of T lymphocytes and abnormal B cell function.

    Defects in B Cell Function

    • Defective antibody responses can result from issues like X-linked agammaglobulinemia (lack of B cell maturation) or hyper-IgM syndrome (impaired class switching).
    • Such deficiencies lead to recurrent pyogenic infections, particularly affecting upper and lower respiratory tract and ear (otitis media).
    • A variety of diseases linked to B-cell function exist, spanning from complete absence of B cells to selective deficits in specific immunoglobulin classes.

    X-linked (Bruton) Agammaglobulinemia

    • X-linked agammaglobulinemia is a disorder localized to the long arm of the X chromosome.
    • The condition primarily impacts young boys, leading to a virtual absence of circulating B cells, resulting in severely low levels of all immunoglobulin subclasses (IgG, IgM, IgA, IgD, IgE).
    • Affected individuals display a lack of antibody production, pre-B cells in the bone marrow, and defective immunoglobulin production caused by a lack of a tyrosine kinase.

    Secondary (Acquired) Immunodeficiencies

    • Major causes of secondary immunodeficiencies include malnutrition, viral infections (e.g., HIV), cancer metastases/leukemias (affecting bone marrow), cancer therapies (chemotherapy/irradiation), corticosteroids (immunosuppressants), and chronic diseases (e.g., diabetes).

    Malnutrition

    • Malnutrition, globally, is a significant cause of immunodeficiency.
    • Deficiencies in calories, essential macronutrients, or micronutrients severely impair immune responses.
    • Severely undernourished individuals have an increased risk of infection.

    Immunodeficiency Secondary to Drug Therapies

    • Immunomodulatory drugs can severely suppress immune functions.
    • Drugs like cyclophosphamide, azathioprine, and mycophenolate mofetil directly affect DNA or its synthesis.
    • Steroids induce lymphocytopenia, monocytopenia, and neutrophilia and hinder cytokine synthesis and T-cell activation and proliferation.

    Human Immunodeficiency Virus (HIV)

    • HIV infection is a major cause of immunodeficiency worldwide, second only to malnutrition.
    • HIV primarily affects CD4+ T cells and macrophages.

    HIV Infection Pathologic Effects

    • HIV pathologic effects are directly linked to interaction with CD4 receptors on T cells and cells expressing the CD4 receptor (macrophages, monocytes, microglial cells).
    • Some HIV strains, termed macrophage-tropic, require CCR5 receptors on cell surfaces to cause infection. Other strains require CXCR4 for binding and cellular uptake.

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    Immunodeficiency States PDF

    Description

    This quiz covers immunodeficiency states, focusing on the diverse group of disorders that result from abnormal immune system function. It delves into the classification of primary immunodeficiencies and examines defects in innate immunity, including phagocytes and the complement system. Test your knowledge on these critical aspects of immunology.

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